Surgical techniques to correct or address spinal problems are turning more and more to non-fusion technologies. One type technology involves spinous process stabilization. Spinous process stabilization is further explained in U.S. patent application Ser. No. 11/128,960 filed May 12, 2005, titled SPINAL STABILIZATION. Another similar technology comprises using conventional pedicle screws and a device to maintain distraction of the spinal segment. Pedicle based systems such as this are further described in U.S. patent application Ser. No. 11/128,962, filed May 12, 2005, titled PEDICLE SCREW BASED VERTEBRAL BODY STABILIZATION APPARATUS. The pedicle based system includes pedicle screws threaded into the pedicles of adjacent spinal segments. A rod connecting the two pedicles is provided with a joint or dampener to allow relative movement between the pedicles. The joint or movement is designed to provide increasing resistance to movement to prevent hard or jolting stops at the maximum extension and flexion movements.
Other conventional pedicle based stabilization system includes a pedicle screw platform threaded into at least a superior and inferior pedicle. Stabilizing cords a placed and spacers inserted between sets of pedicle screws. Once everything is placed, the cords are tightened.
Conventional pedicle based systems, such as the one explained above, provide adequate support, however, any flex of the system is abruptly stopped by either the cord or the spacer. Even if the spacer provides for some flex, the cord provides an abrupt stop in the opposite direction.
Instead of the screw, spacer cord based systems, some pedicle screw stabilization devices provide tracks to allow some movement. For example, the spacer may have elongated slots or tracks on the superior and/or inferior end the spacer to move relative to the pedicle screw, which allows for some relative movement between the superior and inferior vertebrae. The track provides more flex than the spacer/cord systems, but provides abrupt stops in both directions.
Against this background, it would be desirous to develop an improved dynamic spinal stabilization device.